Circuit interrupter



April l, 1947. H. w. GRAYBILL 2,418,171

CIRCUIT INTERRUPTER Filed sept. 14, 1944 3 sheets-sheet 1 April 1 1947- H. w. GRAYBILL 2,418,171

CIRCUIT INTERRUPTER Filed sept. 14, 1944 3 Sheets-*Sheet 3 a Bm WITN/E/SSES: wyf n? y @fm 'Patented Apr. 1, 1947 CIRCUIT INTERRUPTER Howard W. Graybill, Pittsburgh, Pa., asslgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 14, 1944, Serial No. 553,990

' 21 Claims. 1

This invention relates, generally, to electric circuit interrupters and, more especially, to such interrupters which employ a material along the arc path which evolves an arc-extinguishing gas when in proximity to an electric arc, for the purpose of extinguishing the arc.

In circuit interrupters, such as switches designed to open load currents, where repeated operations are required without renewal of any parts of the interrupter, interruption by the use of a blast of arc-extinguishing gas through the arc, which gas is obtained from a solid gas-evolving material activated by the arc, have been found to be objectionable because of the relatively short life of the gas-evolving material. The action of the arc on such gas-evolving materials results in erosion of the material, and while this erosion or wear is small at iirst, being on the order of .001 inch per interruption, it is of importance because these interrupters depend in part for rapid and efficient arc extinction on the high arc voltage obtained by mechanically restricting the arc in a narrow passage which is formed at least in part by the aforesaid gasevolving material. .These narrow arc passages are generally made as narrow as practicable to obtain maximum arc voltage, and consequently, erosion of the gas-evolving material results in widening of the arc passage and consequent lowering of arc voltage andresultantloss in efliciency and speed of interruption. Moreover the erosion becomes progressively worse, because widening of the slot results in a longer arcing time and consequently a greater amount of erosion.

One object of this invention is to provide in 1circuit interrupters of the self-generated gas blast type, novel means for reducing erosion of any one point of the gas-evolving material so as to materially prolong the effective life of such material. A

It has been found that in interrupters of the self generated gas blast type, most of the erosion 'of the gas-evolving material occurs at a relatively small area where initial separation of the interrupter contacts occurs.

Accordingly, another object of this invention is to provide novel means in an interrupter of the type described, for distributing the major portion of the erosion occurring on successive interruptions over different parts of the gas-evolving material.

A more specific object of this invention is to provide in an` interruptor of the self-generated gas blast type, novel means providing for rela- (Cl. 20D- 149) i tive movement of the contacts and gas-evolving material in response to successive interrupting operations, so that different parts of such material are exposed to the maximum eroding effect of the arc on successive interruptions.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken in connection with the attached drawings, in which:

Figure 1 is a partial side elevation view of a switch constructed in accordance with this invention;

Fig. 2 is an end view of the switch shown in Fig. 1, with the arc chute shown in a section taken substantially along the line II--II of Fig. 3;

Fig. 3 is a, longitudinal section taken through the arc chute shown in Fig. 1, with the section being taken substantially on the line III-III of Fig. 2;

Fig. 4 isn-a view similar to Fig. 3, but illustrating the positions of the parts when the switch blade isin its closed circuit position;

Fig. 5 is a longitudinal section view, partially in elevation, illustrating a modified form of this invention;

Fig. 6 is a longitudinal section view of the interrupting device shown in Fig. 5, taken substantially on the line VI-VI thereof;

Fig. 7 is a longitudinal view of still another form of circuit interrupter embodying this invention, with certain of the parts shown in elevation;

Fig. 8 is a transverse section of reduced size, taken through the interrupter shown in Fig. 7, substantially on the line VIII-VIII thereof; and

Fig. 9 is- -a partial longitudinal section View of still another type of interrupter embodying this invention.

This invention is illustrated on Figs. 1 to 4 of the drawings as being embodied in a` load break disconnect. switch of the general type illustrated in H. L. Rawlins Patent No. 2,308,026, issued January 12, 1943, to the same assignee as this invention. Although this invention has certain particular cooperation with a switch ofthe type disclosed in the aforesaid Rawlins patent, it is to be understood that the invention also may be used with other types of circuit interrupters wherein it may also rind-certain novel features of cooperaion.

In general, the particular switch illustrated in Figs. 1 to 4, comprises a pair of supporting insulators 2 and 4, such as porcelain insulators or the like, on which the switc'n proper is mounted.

he supporting insulator 2 is illustrated as having a hinge tongue casting 6 secured thereon as by bolts 1, and it is provided with an integral terminal pad 8 to which a line conductor may be secured in any desired manner. Hinge tongue 6 is apertured for the reception of a pivot bolt IU for pivotally mounting a split switch blade I2. Preferably pivot bolt I is provided at each side of switch blade I2 with spring washers II, for the purpose of providing a predetermined contact pressure between the sides of the split blade I2 and hinge tongue 6.

Supporting insulator 4 is adapted to support a break contact tongue I4 having an integral base which is secured to insulator 4, as by bolts I5, and having an integral outwardly extending terminal pad I1, to which a line conductor may be secured in any desired manner. The outer end of switch blade I2 has the sides thereof secured together by a bolt I8 having spring washers 2I thereon at the outer sides of the blade, and break contact tongue I4 is preferably provided with a slot (not shown) for receiving bolt I8 in the closed position of the switch illustrated in Fig. 1. An actuating handle I6 is adapted to be secured between the outer ends of the sides of blade I2, and is preferably provided with a hook eye I8 for the reception of a hook stick operating member or the like.

It is believed apparent that the structure thus far described is that of a conventional disconnect switch having a blade I2 pivotally mounted at one end for movement of the other end into and out of engagement with break contact tongue I4, to close the circuit when in engagement, and to provide a safe air gap in the circuit when out of engagement.

For the purpose of interrupting load currents, switch blade I2 is provided with an auxiliary snap-acting blade 20 adapted to be mounted on one side of blade I2. The mounting for auxiliary blade 20 comprises a mounting fixture 22 having spaced plates, one of which is adapted to lie against the inner end of auxiliary blade 28 and be secured thereto as by screws 24. The other plate 25 of mounting fixture 22 is adapted to lie against the adjacent side of split blade I2. The auxiliary blade 20 and mounting fixture 22 are apertured for the reception of a pivot bolt 26 so as to be freely rotatable on this bolt, which is secured in main blade I2. Mounting fixture 22 has the plates 25 thereof maintained in spaced apart relation by integral transversely extending connecting bars 28 and 30. The plate 25 of mounting fixture 22 which lies adjacent main blade I2 is notched, as shown, at 32 to receive a stop screw 34 mounted in main blade I2. The purpose of stop screw 34 is to limit pivotal movement of auxiliary blade 20 relative to main blade I2. A spring 36 is coiled about pivot bolt 26 and reacts between one screw 24 and stop screw 34 to normally bias auxiliary blade 20 in a counterclockwise direction about pivot bolt 26 to maintain stop screw 34 in engagement with the side of notch 28, wherein the auxiliary blade lies substantially parallel to main blade I2, so as to be received in an arc chute 3l positioned at one side of break contact tongue I4.

The structure thus far described is substantially identical with that disclosed in the aforementioned Rawlins patent, and, accordingly, for a more complete description of the parts and their operation, reference is hereby made to such Rawlins patent. This invention is primarily con.. cerned with the construction of arc chute 31 and with certain aspects of its cooperation with the switch structure heretofore described. Arc chute 31 comprises a pair of plates 38 which may be machined or molded complementary in shape. Plates 38 may be of any desired insulating material but are preferably of an insulating material which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, such, for example, as fiber, a synthetic resin, or the like. The plates 38 are each provided with integral flange portions 40 and 42 along adjacent edges thereof, for the purpose of spacing the plates a predetermined distance apart when the plates are assembled with the flanges in abutting relation, and secured together, for example, as by bolts 44. Flanges 42 are interrupted adjacent flange 40 to receive the upright arm 46 of an angled supporting bracket, the base portion 48 of which is adapted to be secured to insulator 4 between the insulator and. the base of break contact tongue I4. Each plate 38 is also preferably recessed to receive a contact jaw 50, with one jaw located at each side of upright arm 46 of the supporting bracket, and secured in position by one of bolts 44. Each plate is also provided with a generally circular depressed portion 52 for receiving a circular disk 54 also of insulating material, and particularly of an insulating material which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, such, for example, as the materials given above for plates 38.l Although circular disks 54 are of a gasevolving insulating material, they need not be of the same material as plates 38, especially if plates 38 are of an inert insulating material.

Disks- 54 of gas evolving material are rotatably mounted on plates 38, as' by rivets 56, and are provided about their periphery with ratchet teeth 58, adapted to cooperate on the one hand with a spring holding pawl secured to a flange 40 in any desired manner, such, for example, as by screws 6I. Ratchet teeth 58 on disks 54 are also adapted to cooperate with a pawl lever 62 pivotally mounted between plates 38 on a pivot pin 64. A spring 66 coiled about pivot pin 64 is provided for biasing pawl lever 62 in a clockwise direction about pivot 64, as viewed in Figs. l, 3, and 4, so that in the open circuit position of the switch, pawl lever 62 is held against the adjacent portion I2 of flange 40, as shown in Fig. 3. Pawl lever 62 is provided at its outer end with a spring pawl portion 68 adapted to engage ratchet teeth 58, and the inner end of pawl lever 62 is provided with a. transversely extending toe I0 positioned in the path of movement of auxiliary switch blade 28, for a purpose to be described. It will be observed that arc chute plates 38 are provided with depressions opening into circular depression `52 for receiving pawl 68, pawl lever 62, and contact jaws 58. Arc chute plates 38 are also provided With an outwardly flared entrance 14, at the point where auxiliary blade 20 enters the chute during a circuit closing operation.

In the operation of the switch, and assuming it is desired to open the circuit by moving the switch from the closed circuit position shown in Figs. 1 and 4, a hook stick or other operating member is inserted in hook eye I8, and main blade I2 is pulled away from break contact tongue I4. Howv ever, auxiliary blade 20 is held frictionally between contact jaws 50, while the auxiliary blade rotates on pivot bolt 26 and stresses spring 36. This movement of the parts continues until main switch blade I2 is separated a substantial distance from break contact tongue I4, and the other side of notch 32 in plate 25 of mounting fixture 22 engages stop screw 34, whereupon continued opening movement o! main switch blade I2 causes auxiliary blade 20 to be pulled out of contact jaws 50. As soon as auxiliary blade 20 escapes from frictional engagement with contact jaws 50, its biasing spring 36 acts-to rapidly move the auxiliary blade relative to main blade I2 in a pivotal manner about bolt 26 to restore it to the position shown in Fig. 1 where it lies alongside main blade I2. Preferably this snap action of auxiliary blade 20 takes place substantially throughout the narrow slot formed between arc chute plates 38 and disks 54 therein, so that the arc drawn upon separation of auxiliary blade 20 from contact jaws 50 will be very rapidly elongated through the arc chute and extinguished therein. The arc-extinguishing action of the arc chute is due in part to the rapid elongation of the arc -by snap movement of auxiliary blade 20, which rapidly increases the arc voltage, and in part to physical confinement of the arc in the narrow space between the arc chute plates and disks 54, and nally by the action of arc-extinguishing gas evolved from the material of disks 54 and plates 38 if the latter be made of gas evolving material, which acts to supply a blast of unionized gas through the arc and out the open sides of arc chute 31, to further increase the resistance of the arc path at current zero by replacing the ionized particles in the arc path by the unionized particles of the evolved gas. These several arc-extinguishing actions jointly produce extremely efcient arc-extinguishing action. The space or slot defined between arc chute plates 38 and disks 54 is made as small as possible, being limited only by the thickness of auxiliary blade 20.

After the circuit has been opened in the manner described above and it is desired to close the switch, main blade I2 is rotated in the opposite or clockwise direction about its pivot bolt I0 by means of hook eye I8, and this carries auxiliary blade 20 `along with it into arc chute 31. After main blade I2 and auxiliary blade 20 have engaged their respective contacts, and prior to the attainment of fully closed position, it will be observed that the outer end of auxiliary blade 20 will engage the toe 10 of pawl lever 62 to rotate the pawl lever in a counterclockwise direction about its pivot 64. This causes pawl portion 58 of the pawl lever to engage a ratchet tooth 58 on insulating disks 54 to rotate the disks a distance corresponding to approximately the distance between ratchet teeth in a clockwise direction. Spring holding pawl 60 isprovided for the purpose of preventing retrograde movement of disks 54 when the switch is opened, and pawl lever 62 is moved from the position shown in Fig. 3 clockwiseto the position shown in Fig. 4 by its biasing spring 66. This permits pawl portion 68 of the pawl lever to engage the next ratchet tooth in a counterclockwise direction when the switch is reclosed. It is Vthus apparent that each time the switch is closed, disks 54 are rotated a predetermined amount in a clockwise direction. It will be observed that the outer ends of spring holding pawl 60 and pawl portion 68 are bifurcated, to permit auxiliary'blade 20 to move between the furcations thereof during its opening and closing movements. Also, pawl lever 62. preferably is apertured to provide a space for coil spring 6B, and toe 10 extends substantially transversely with respect to blade 20.

As previously stated, each time the circuit is opened, the action of the arc on the gas evolving material comprising disks 54 and plates 38 has an eroding effect thereon, so that the width of the` slot in which the arc is drawn is very slightly increased by each circuit interrupting operation. Such erosion. of course, varies with the value of current interrupted and with the length of time the arc is maintained. Tests have shown that such erosion is very much greater at a point closely adjacent the point of initial contact separation than elsewhere, so much so that erosion at a point an inch or more away from the stationary contact jaws 50 is negligible by comparison. Furthermore, in an arc chute having stationary walls, it is possible to interrupt a given value of current at a given voltage at the end of the first half cycle when the arc'chute is new. However, after about operations at the same current and voltage, the chute will show erosion from one-eighth to one-fourth of an inch over an area about one-half of an inch in diameter closely adjacent the stationary contacts. Moreover. after this number of. operations, the arc A,during interruption will continue for as many as four to six half cycles, with a resulting erosion from ve to ten times that occurring when the chute is new. This becomes progressively worse as the number of operations is increased, and eventually reaches a point where the arc is not extinguished within the chute, but is drawn outside the chute, resulting in a flashover and failure. With an arch chute constructed in accordance with this invention wherein disks 54 are in proximity to stationary contact jaws 50, and where these disks are moved so as to present different surfaces to successive arcs, it is obvious that the erosion of a great number of successive arcs is distributed over a relatively wide area of disks 54, so that the width of the arc passage is increased but a small amount, if any, even after a relatively large number of successive circuit interrupting operations have occurred. With a structure such as that disclosed herein wherein different surfaces of gas evolving material are exposed in proximity to successive arcs, it is apparent that the eihcient life of such an arc chute will be multiplied a number of times substantially equal to the nurnber of ratchet teeth on disks 54. In other words. when a chute constructed in accordance with this invention is new, it will operate with the same characteristics as the first operation of a new chute having fixed walls, for the number of operations required before disks 54 are rotated one complete revolution. It is only after this number of successive operations has occurred, that any eroded surface at all is positioned in proximity to the arc, and because the arcing time on these rst operations has been very short, the erosion is correspondingly very low. Each complete revolution of disk 54 thus results in an amount of erosion of the gas evolving' material at any one point, substantially equal to the resulting from a single operation of a chute having xed walls. This invention, therefore, results in multiplying the life of the chute by approximately the number of operations required to rotate disks 54 one complete revolution.

In the embodiment of the invention shown in Figs. 5 and 6, there is illustrated a circuit interrupter comprising a tubular housing 16 of any desired insulating material, such for example, as a molded insulating material or the like. A cap structure 18 is threaded on the lower end of tubular housing 16, and the cap structure' is apertured for the reception of a terminal bolt 80 having a shoulder 82 adapted to be drawn against the inner side of cap structure 18 by a nut 84. Preferably integral with terminal bolt 80 there is provided a supporting post 86 extending up into housing 18, for the purpose. of rotatably supporting thereon a filler plug 88. The filler plug is positioned centrally of the housing and extends longitudinally thereof for the purpose of forming the inner wall of an annular arc chamber. In order to assist in extinguishing arcs formed in proximity to the outer surface of filler plug 88, it is preferably composed of an insulating material which is capable of evolving an arc extinguishing gas when in proximity with an electric arc, such for example, as fiber, a synthetic resin, or the like. Filler plug 88 is provided with a longitudinally extending recess 90 therein for receiving supporting post 88, and bearings 92 are provided between the post and filler plug to rotatably mount the plug on the post. As shown, bearings 92 are of the ball type, so that the plug will be freely rotatably mounted on the post. A tubular member 94, also of a gas-evolving insulating material like plug 88, is rotatably mounted in housing 'i6 by ball bearings 93 or the like, located adjacent opposite ends thereof, and held in place against a shoulder provided adjacent the lower end of housing 'i8 by a threaded collar 96 threadedly engaged in the upper end of housing '16.

Spaced contact arms are provided integral with terminal bolt 80, to provide spaced contact jaws located at one point at the lower end of the annular space between tubular member 94 and plug 88, for receiving therebetween the lower end of a contact rod |02 in the closed Icircuit position of the interrupter. Contact rod |02 is illustrated as mounted on the transverse head of a contact actuating rod |06. Any suitable means may be provided for longitudinally moving contact actuating rod |04 to move the lower end of contact rod |82 into and out of engagement between contact jaws |00.

The structure thus far described operates in a known manner to interrupt the circuit and extinguish any arc drawn during a circuit interrupting operation, by confining such arcs in the narrow annular space between tubular member 94 and plug 88, while subjecting the arc to a blast of the gases evolved from the material of plug 88 and tubular member 84. The arc-extinguishing action thus comprises a physical restriction of the Aarc core to create a high arc voltage, acting in conjunction with a gas-blast which acts to replace ionized particles in the arc path with unionized particles, so as to prevent restriking of the arc at a current zero.

In order to prevent undue wear or erosion of plug 88 or tubular member 94, these members are mounted for rotation substantially about their longitudinal axis, as explained above, and means are provided for rotating these members, so that successive arcs are not struck in proximity with the same portions of these members. For producing rotation of plug 88 and tubular member 94, the upper end of plug 88 is provided with a series of annularly arranged notches |06, and the upper end of the tubular member is provided with an annular series of notches |08. Spring actuating pawls I|0 and I|2.are provided on the underside of head |05 of contact actuating rod |04, for engagement with notches |08 and |06, respectively, when the actuating rod is moved to close the circuit. In a similar manner, the

with spring retaining pawls |20 and ||8, respec-- tively. The pawls are mounted in any desired manner on their respective supports, for example, as by screws ||I.

The interrupter is shown in Fig. 5 in its open l circuit position, and it will be observed that, when actuating rod |04 is moved downwardly to close the circuit, spring pawls |I0 and ||2 will engage with the respective notches |08 and |08, s0 that continued downward movement bends the pawls to cause rotation of plug 88 and tubular member 94 about their longitudinal axis. Re-` tainer pawls I|8 and |20 are arranged to slip over their respective notches i I4 and ||8 to permit such rotation of the plug and tubular member when the switch is closed, but prevent rotation of these parts in the opposite direction. Accordingly, when the interrupter is opened by mov ing the actuating rod upwardly, pawls I8 and |20 will retain plug 88 and tubular member 8l at the positions to which they were advanced by pawls I|0 and I2 on the preceding circuit closing operation. As shown in Fig. 6, pawls ||0 and II2 are of the same extent, and accordingly will be flexed and rotate the plug and tubular member the same linear amount during closing of the interrupter. However, since notches |08 and |88 are at different radii from the longitudinal axis of the interrupter, they will be caused t'o rotate different angular amounts on each circuit closing operation, so that the portions thereof which were exposed to the arc on the preceding circuit interrupting operation will be displaced from each other as well as being advanced to a position away from proximity with the arc. It can thus be seen, that the interrupter shown in Figs. 5 and 6 is not only capable of presenting fresh surfaces of gas-evolving material to successive arcs, but additionally moves the inner and outer walls of the arc passage different angular amounts, to prevent any portions of these walls which are subjected to one arc from becoming lined up opposite each other so as to both be again subjected to an arc at the same time, on some future circuit interrupting operation. Moreover, it will be noted that pawls ||0 and ||2 are inclined in opposite directions, so that upon closing the interrupter, plug 88 and tubular member 94 will be rotated by these pawls in opposite directions, to thus further increase displacement of any two portions of plug 88 and tubular member 94 which have been subjected to one arc, and therefore further lessen the chances that these same two portions might become lined up opposite each other again, to be subjected to some future arc at the same time.

In Figs. '7 and 8 of the drawings, there is illustrated still another type of circuit interrupter and the manner in which this invention may be applied thereto. This interrupter is illustrated as being mounted in a tubular casing |22 of insulating material, such for example, as a molded insulating material, or the like. The lower end of casing |22 is threaded for the reception of a threaded closure plug |24 also of insulating material, similar to that of casing |22. Closure plug |24 is adapted to support the connecting portion of a generally U-shaped contact structure |28 having projecting contact portions |28 mounted on the inner side of the legs thereof adjacent their opposite ends. Preferably contact portions |28 are of a different material from contact structure |26, and should be oisome arc resistant material, such for example, as a tungsten alloy. Contact structure |26 is centrally apertured so as to receive and be secured on the end of a terminal bolt |30. Bolt "|30 issecured to the contact structure in any desired manner, such for example, as by welding or the like, and itself is secured in an aperture provided in closure plug |24 by a nut |32 threaded on the outer end thereof.

A tubular member |36 of insulating material,

preferably of a gas-evolving insulating material such as the material forming the arc passages in the previously described embodiments of this invention, is rotatably mounted within casing |22 by bearings |34, preferably of the antifriction ball type. A securing collar |38 is threadedly engaged with the inner wall of casing |22 to hold tubular member |36 in engagement with a shoulder on theinnerwall of casing |22 located adjacent contact portions |28, Contact actuatingrod |40 extends into casing |22, 'and is provided at its inner end with an enlarged'contact head |42 of a 'size to engage between contact portions |28. Contact head 42 is provided Awith a central recess which is threaded for engagement with a threaded supporting rod |44 for the purpose of supporting a contact follower |48. Follower |48 is also of insulating material, preferably an insulating material which is capable of evolving y a gas to extinguish the arc, like tubular member eration with spring retaining pawls |60 mounted on the underside of contact head 42. Tubular member |36 is provided substantially centrally around the outside thereof with'a series of notches |62 for engagement with a spring retaining pawl |64 secured on the inner wall of casing 22. The upper end of tubular member |36 is also provided with an annular series of notches |66 adapted to Vbe engaged byV spring actuating pawls |68 secured on transversely oppositely extending arms |10 mounted on actuating rod |40.

The operation of the interruptor shown in Figs. '1 and 8 is quite similar to that shown in Figs. and 6. The interrupter is illustrated in Fig. 7 in the open circuit position, so that when 10 bular member |36. The arc is thus extinguished in substantially the same manner as in the embodiment of the invention shown in Figs. 5 and 6, the only substantial difference being that the annular arcing space, in this embodiment of thc invention, may be much narrower because it is not limited by the size of the conductor necessary to carry the current as is the interrupter shown in Figs. 5 and 6, Where it is necessary that the current-carrying member move through the arc space. Here, as in the embodiment of the invention shown in Figs. 5 and 6, follower |46 and tubular member |36 may be rotated each time by their respective actuating pawls in the same rotative direction, but are preferably rotatedv in opposite directions as shown on the drawings. It will also be observed that retainer pawls |60 and |64 will act to retain follower |48 and tubular member |36 at the position to which they are advanced by the actuating pawls, so that the;

arcs of successive circuit interrupting operations? are exposed to different surfaces of follower |48 and tubular member 36.

The particular interrupter illustrated in Fig. 9 of the drawings is similar in most respects to that disclosed in the patent to J. M. Wallace and H. L. Rawlins 2,286,131, issued June 9, 1942, to the same assignee of vthis invention. This interrupter, in general, is supported between a metallic end cap structure |14 and a supporting ring |16 spaced therefrom, and held in spaced xed relation by threaded engagement with the opposite ends of a tube 18 of insulating material, such as a molded insulating material or the like. For added insulating qualities, an outer weatherproof tube of insulating material |80 may also be held between cap |14 and ring |18 in engagement with packing material |82 positioned at opposite ends actuating rod |48 is moved downwardly to close V the circuit, it will be observed that actuating pawls |68 will engage notches |66 to rotate member |36 a predetermined increment about its lon.-

gitudinal axis, and at the same time, notches |54 on follower |48 will engage actuating pawls |56 to cause rotation of the follower substantially the same linear amount about its longitudinal axis. When the interruptor is moved back upwardly, to move contact head 42 out of engagevided a conductor rod |86 having a tubular cover |88 thereon which is spaced from tubular lining |84, to form an annular arc space |92 therebetween. Cover |88 is also preferably of a gas- -ev0lving insulatingmaterial similar to liner |84.

Preferably the outer end of arcing space |92 adjacent cap |14 is iilled by an annular plug |90 also of insulating material, which is threadedly engaged with liner '|84 and cover |88.

The contact structure and actuating mechanism' are supported within a metal casing |93 secured to supporting ring |16, as bybolts |9|, only one of which is shown. Supporting plates |94 are secured to supporting ring |16 within casing |93, for the purpose of supporting therebetween a pair of opposed contact arms |96 on pivot pins |98, which are located at opposite sides of the arcing space |92. The outer ends of contact arms |96 are directed toward each other, for engagement in opposite sides of a groove provided in a contact .ring 200 mounted on the in'ner end of conductor rod |86, and-held in place by a tapered-nut 202. Contact arms |86 are biased to engage contact ring 200 by compression springs 206 mounted on toggle. levers 204, which are pivoted to the inner ends of the contact arms, and slotted at their other ends for sliding on support Supporting plates |94 (onLv one oi which is shown) each has an arcuate extension 2|2 extending toward the opposite wall of casing |93, for the purpose or slidably supporting therebetween an arc-extinguishing tube 2| 0. Extensions 2|2 of the supporting plates are preferably connected at spaced points by rings 2|4, 2|B and 2|1. The supporting plate extensions 2 |2 are each provided with a guide slot 2|8 for a purpose to be described. Arc-extinguishing tube 2| 0 is provided at its outer end with an actuating member 226 having an extension threadedly mounted in the adjacent end of the tube to be secured thereto, and this member is rotatably mounted in a bearing sleeve 228 located between thehead of actuating member 226 and the adjacent end of arc-extinguishing tube 2|0, by ball bearings 230, or the like. Bearing sleeve 228 is provided with actuating pins 220 at opposite sides thereof to be received in guide slots 2I8 to prevent rotation of the bearing sleeve about its longitudinal axis, and these pins 220 also extend into notches 222 provided in the outer ends of actuating levers 224 (only one shown).

In operation, the contact arms |96 are separated from contact ring 200, and the resulting arc is elongated in the annular arc space |92 in response to movement of actuating lever 224 to the left. Actuating lever 224 may be actuated inV any desired manner, preferably in the manner illustrated in the aforementioned Wallace and Rawlins patent, which also contains a more complete description of the various parts of the interrupter and their mode of operation. Accordingly, for a better understanding thereof, reference is hereby made to the aforesaid Wallace and Rawlins patent.

In accordance with this invention, arc-extinguishing tube 2|0 is rotatably mounted substantially about its longitudinal axis, as described above, and means are provided for rotating this tube a predetermined increment between successive circuit interrupting operations. This rotating means comprises the provision of an annular series of notches 232 provided on the outer end of actuating member 226, for engagement with a spring actuating pawl 234 secured to the adjacent wall of casing |93, so as to engage the pawl whenever arc-extinguishing tube 2||J reaches its full open circuit position to ben'd the pawl and cause rotation of the arc-extinguishing tube 2|!! a predetermined amount. This will occur as stated when tube 2|0 moves to its open circuit position, so that on successive circuit opening operations, different surfaces of tube 2|() will be presented to the arcs formed on such successive circuit opening operation. No retaining pawl is illustrated in connection with this embodiment of the invention because the friction between arcextinguishing tube 2|0 and its guide plate extensions 2|2 will tend to hold the tube at any adjusted position. However, such a retainer pawl may be provided if desired, such for example, as between bearing sleeve 228 and the adjacent portion of actuating member 22E, similar to the arrangement shown in Figs. 7 and 8 between housing |22 and tubular member |36.

Having described preferred embodiments of the invention in accordance with the patent statutes, it is again emphasized that this invention should not be limited to the particular embodiment of circuit interrupter with which it is disclosed, -because it will be obvious, particularly to persons skilled in the art, that many modifications and changes may be made therein, and that the in- 12 vention is adapted for use with other types of circuit interrupters. Accordingly, it is desired that the invention be interpreted as broadly as possible in accordance with the following claims.

I claim as my invention:

1. In a circuit interrupter, means of insulating material defining opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, separable contacts adapted when separated to establish an arc at one point in said passage and draw out the arc through said passage, at least a portion of said gas evolving material being mounted for pivotal movement on an axis which extends transversely of said passage and is located at a point spaced from said point of arc establishment in the direction of arc drawing movement, and means responsive to successive circuit interrupting operations to rotate said portion of said material an amount sufficient to expose different parts of said rotatable portion of said material to said point of arc establishment on such succeeding circuit interrupting operations.

2. In a circuit interrupter, means of insulating material defining opposed inner wall portions of a narrow slot arc passage, said material being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, separable contacts adapted when separated to establish an arc at one point in said passage and draw out the arc through said passage, at least the portions of said gas evolving material located at opposite sides of said slotin proximity to said point of arc establishment being mounted for movement relative to said point, and means responsive to successive circuit interrupting operations to move said portions of said material an amount suillcient to expose different parts of said movable portions of said material to said point of arc establishment on such suc ceeding circuit interrupting operations.

3. In a circuit interrupter, means of insulating material defining opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable oi.' evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, separable contacts adapted when separated to establish an arc at one point in said passage to draw out the arc through said passage, at least a portion of said gas evolving material being mounted for movement relative to said point of arc establishment, andy ratchet mechanism associated with said contacts and said movable portion of gas evolving material and arranged to move said portion of said material an amount sufhcient to expose diierent parts of said movable portion of said material to said point of arc establishment on such succeeding circuit interrupting operations.

4. In a circuit interrupter, means of insulating material dening opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, separable contacts adapted when separated to establishan arc at one point in said passage and draw out the arc through said passage, at least a portion of said gas evolving material being mounted for movement relative to said point of arc establishment, and ratchet mechai 13 nism associated with said contacts andsaid movable portion of gas evolving material and arranged to move said movable portion o f said material in response to movement of said contacts into engagement an amount suiiicient to expose successive parts of said movable portion of said material to said point of arc establishment on such succeeding circuit interrupting operatlons in response to movement.

5.,In a circuit interrupter, means of insulating material deiining opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc in extinguishing the arc, a contact supported adjacent one edge of said slot, a cooperating contact mounted for movement through said slot into and out of engagement with said first-mentioned contact, at least the portion of gas evolving material at one side of said slot adjacent said first-mentioned contact being mounted for movement relative to said first-mentioned contact, and means responsive to movement of said movable contact for moving said movable portion of gas evolving material to thereby expose different parts of said materia] to successive arcs established by successive circuit opening movements of said movable contact.

6. In a circuit interrupter, means of insulating material defining opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, a contact supported adjacent one edge of said slot, a cooperating contact mounted for movement through said slot into and out of engagement with said first-mentioned contact, at least the portion of gas evolving material at one side of said slot adjacent said first-mentioned contact being mounted for movement relative to said iirst-mentioned contact, and means responsive to movement of said movable contact into engagement with said iirst-mentioned contact for moving said movable portion of gas evolving material to thereby expose diiierent parts of said material to successive arcs established by successive circuit opening movements of said movable Contact.

7. In a circuit interrupter, means of insulating material defining at least inner wall portions of an annular arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to extinguish said arc, means for establishing an arc longitudinally in said passage, and means responsive to successive circuit opening operations for causing relative annular movement of the first two mentioned means so that diierentportions of said gas-evolving material are exposed to successively established arcs.

8. In a circuit interrupter, tubular means at least partially of insulating material for delining the outer surface of an arc passage, means at least partially of insulating material positioned in said tubular means and spaced therefrom at least during each circuit interrupting operation to define the inner wall of said passage, at least a portion of one of said means forming a wall of said arc passage being of an insulating material which is capable of evolving an arc-extinguishing gas, means for establishing an arc longitudinally of said passage, and means for rotating at least said one wall-forming means substantially about its longitudinal axis a predetermined increment in response -to successive circuit interrupting operations to thereby present different parts of said gas-evolving material to such successive arcs.

9. In a circuit interrupter, tubular means at least partially of .insulating material for delining the outer surface of an arc passage, means at least partially of insulating material positioned in said tubular means and spaced therefrom at least during each circuit interrupting operation to deline the inner wall of said passage, at least portions of the walls of said arc passage being of an insulating material which is capable of evolving an arc-extinguishing gas, means for establishing an arc longitudinally of said passage, and means for rotating said `wall-forming means substantially about their longitudinal axes a predetermined increment in response to successive circuit interrupting operations to thereby present different parts of said gas-evolving material to such successive arcs.

l0, In -a circuit interrupter, tubular means at least partially of insulating material for delining the outer surface of an arc passage, means at least partially of insulating material positioned in said tubular means and spaced there- Vfrom at least during each circuit interrupting operation to define the inner wall of said passage, at least portionsof the walls of said arc passage being` of an insulating material which is capable of evolving an arc-extinguishing gas, means forA establishing an arc longitudinally of said passage, and means for rotating said wall-forming means in opposite directions substantially about their longitudinal axes a predetermined increment in response to successive circuit interrupting'operations to thereby present different parts of said gas-evolving material to such successive arcs.

11. In a circuit interrupter, tubular means at least partially of insulating material forming an arc passage, separable contacts one of which is movable away from the other substantially 1ongitudinally through said passage to draw out the arc in a circuit interrupting operation, means at least partially of insulating material having a cross sectional area at least slightly less than the cross sectional area of said passage adapted to follow said movable contact through said passage during a circuit interrupting operation to restrict the arc, at least one of said means having at least a portion of its surface exposed to said arc of an insulating material which is capable of evoling an arc-extinguishing gas when in proximity to an electric arc, and means for rotating at least said one means substantially about its longitu-` dinal axis a predetermined incrementin response to successive circuit interruptingy operations to thereby present different parts of said gas-evolving material to such successive arcs.

12. In a circuit interrupter, tubular means at least partially of insulating material for defining the outer surface of an arc passage, means at least partially of insulating material positioned in said tubular means and spaced therefrom at least during each circuit interrupting operation to define the inner Wall of said passage, at least portions of the walls of said arc passage being of an insulating material which is capable of evolving an arc-extinguishing gas, means for establishing an arc longitudinally of said passage. and means for rotating said wall-forming means sub.

stantially about their longitudinal axes in respense to successive circuit interrupting operations to thereby present dilerent parts of said gas-evolving material to such successive arcs.

13. In a circuit interrupter, tubular means at least partially of insulating material forming an arc passage, separable contacts one of which is movable away from the other substantially longitudinally through said passage to draw out the arc in a circuit interrupting operation, means at least partially of insulating material having a cross sectional area at least slightly less than the cross sectional area of said passage adapted to follow said movable contact through said passage during a circuit interrupting operation to restrict the arc, said means having at least portions of their surfaces exposed to said arc of an insulating material which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, and means for rotating said means substantially about their longitudinal axes a predetermined increment in response to successive circuit interrupting operations to thereby present diierent parts of said gas-evolving material to such successive arcs.

1,4. In a circuit interrupter, tubular means at least partially of insulating material forming an arc passage, movable means at least partially of insulating material adapted to move into said passage during a circuit interrupting operation to restrict the arc in said space, said movable means having at least a portion of its surface exposed to sa'id arc of an insulating material which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, and means for rotating said movable means substantially about its longitudinal axis a predetermined increment in response to successive circuit interrupting operations to thereby present different parts of said gas-evolving material to such successive arcs.

15. In a circuit interrupter, means of insulating material defining opposed inner wall portions of a narrow slot arc passage, said material of at least one inner wall portion being capable of evolving an arc-extinguishing gas when in proximity to an electric arc to aid in extinguishing the arc, separable contacts adapted when separated to establish an arc at one point in said passage and draw out the arc through said passage, at least the portions of said gas-evolving material located at opposite sides of said slot in proximity to said point of arc establishment being mounted for movement relative to said point, and means responsive to successive circuit interrupting operations to move said portions of said material in opposite directions an amount suillcient to expose different parts of said movable portions of said material to said point of arc establishment on such succeeding circuit interrupting operations.

16. In a circuit interrupter, spaced walls dening an arc passage therebetween at least when an arc is struck in said passage, said space between said Walls being relatively small so that said walls will be in close proximity to the arc, at least inner surfaces of said walls being of an insulating material and at least one inner wall of said passage comprising at least in part insulating means which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, means for establishing an arc in said passage, and means responsive to an operation of said interrupter for automatically relatively moving at least a part of said gas-evolving material and said arc-establishing means in a direction extending generally in the direction of the inner surface of said one inner wall without disturbing 16 the spacing of said walls, so that different portions of said gas-evolving material will be brought into proximity with successive arcs.

17. In a circuit interrupter, spaced walls defining an arc passage therebetween at least when an arc is struck in said passage, said space between said walls being relatively small so that said Walls will be in close proximity to the arc, at least inner surfaces of said walls being of an insulating material and at least one inner wall` of said passage comprising at least in part in' sulating means which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, means for establishing an arc in said passage, at least a portion of one of said means being mounted for movement relative to the other of said means in the direction of the inner surface of said one inner wall, and'means for automatically moving said one means between successive circuit interrupting operations without disturbing the spacing of said walls, so that different portions of said gas-evolving material will be brought into proximity with successive arcs.

18. In a circuit interrupter, spaced walls defining an arc passage therebetween at least when an arc is struck in said passage, said space between said Walls being relatively small so that said Walls will be in close proximity to the arc, at least inner surfaces of said walls being of an insulating material and at least one inner wall of said passage comprising at least in part insulating means which is capable of evolving an arcextinguishing gas when in proximity to an electric arc, means for establishing an arc in said passage along a predetermined path, at least the portion of said gas-evolving material located in proximity to the initially formed portion 'of said arc being mounted for movement at an angle to said predetermined path, and means responsive to successive circuit interrupting operations to move said portion of said gas-evolving means an amount suiiicient to expose a different portion of said gas-evolving material to said initial part of the arc on a succeeding circuit interrupting operation Without disturbing the spaced apart relation of said wall portions.

19. In a circuit interrupter, spaced walls defining an arc passage therebetween at least when an arc is struck in said passage, said space between said Walls being relatively small so that said walls will be in close proximity to the arc, at least inner surfaces of said walls being of an insulating material and at least one inner wall of said passage comprising at least in part insulating means which is capable of evolving an arcextinguishing gas when in proximity to an electric arc, separable contacts adapted when separated to establish an arc at one point in said passage and draw out said arc through said passage, and means actuated by at least one of said contacts for relatively moving at least a part of said gasevolving material and said contacts in a direction extending generally in the direction of the inner surface of said one inner wall without disturbing the spacing of said walls, so that different portions of said gas-evolving material will be brought into proximity with successive arcs.

20. In a circuit interrupter, tubular means at least partially of insulating material for defining the outer surface of an arc passage, means at least partially of insulating material positioned in said tubular means and spaced therefrom at least during each circuit interrupting operation to define the inner wall of said passage, at least portions of the walls of said arc passage being of an insulating material which is capable of evolving an arc-extinguishing gas, means for establishing an arc longitudinally of said passage, and means for rotating said wall-forming means substantially about their longitudinal axes predetermined different increments, respectively, in response to successive circuit interrupting operations to thereby present different parts of said gas-evolving material to such successive arcs.

21. A switch, comprising, a support, a disconnect contact, arc passage means and a ilrst interrupting contact all mounted in proximity on said support with said iirst interrupting contact permanently located in said passage means and electrically connected with said disconnect contact, aswitch blade mounted for movement on said support into and out of engagement with said disconnect contact, a second interrupting A contact mounted on said blade for movement thereby to and away from said passage and through said passage into and out of engagement with said first interrupting contact, spaced walls defining said arc passage therebetween at least when an arc' is struck in said passage, the space between said walls being relatively small so that said walls will be in close proximity to arcs struck 18 upon separation of said interrupting contacts, at least inner surfaces of said walls being of an insulating material and at least one inner wall of said passage comprising at least in part insulating means which is capable of evolving an arc-extinguishing gas when in proximity to an electric arc, and means responsive to an operation of said switch for automatically eiectingrelative movement between at least a part of one of said passage Walls and said rst interrupting contact in a plane parallel to the plane of movement of said second interrupting contact and switch blade but in a direction at an angle to the direction of such movement. v

HOWARD W. GRAYBILL.

REFERENCES CITED The following references are of record in the ille of this patent: 

